BP has been cleared of the most serious allegations made by a whistleblower over its Atlantis deepwater production platform in the Gulf of Mexico.

A US government investigation found that BP's database of thousands of documents for components of the platform was "disorganised, inadequate and confusing".

Industry experts liken the database to an "operating manual" that is critical to being able to respond to an accident or technical problem, particularly if they involve components thousands of metres under the water.

But the investigation found that the allegations that engineers on board the platform lacked access to the right documents was "without merit" and said no evidence had been found that the database deficiencies made for unsafe operating conditions.

The investigation, which had also been called for by members of Congress, said that there were no grounds to force BP to suspend operations or remove its licence. But it did make recommendations to tighten up existing regulations to require all operators to keep up to date the "as-built" drawings and documents of components that show how they have been installed on each platform.

The whistleblower, Ken Abbott, who worked for a BP subcontractor on the Altantis rig before being fired, made the allegations before the Deepwater Horizon rig exploded. The discredited – and now dissolved – offshore regulator MMS eventually began an investigation following pressure from members of Congress.

BP had always denied the claims that were laid against it, although some appeared to have been substantiated by its own independent safety ombudsman.